Labelling machine with pneumatic monitor

ABSTRACT

A high speed labelling machine which picks up and lays down labels by means of an &#39;&#39;&#39;&#39;apertured&#39;&#39;&#39;&#39; pressure-and-vacuum head includes a monitoring system for assuring against faulty labelling. The monitoring system employs a pressure switch rather than a vacuum switch - to check for vacuum during the monitoring operation. Use of a pressure switch as a vacuum detector is made possible by means of a chamber connected to the head, and to which an auxiliary internal pressure is applied ... the pressure switch being also connected to the chamber.

United States Patent [191 Kahw ati et al.

[ LABELLING MACHINE WITH PNEUMATIC MONITOR [75] Inventors: Ghassan N.Kahwati, Rochester;

Allen C. Mercer, Brockport, both of NY.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Nov. 19, 1971 [21] Appl. No.: 200,301

[52] U.S. Cl 214/1 BS, 294/64 R [51] Int. Cl.

[58] Field of Search .i 294/64 R, 65; 214/1 B, l BS,1BT,1BH,1BV

[56] References Cited UNITED STATES PATENTS 5/1971 Schuler 294/64 R11/1965 Carliss.....

5/1970 Flup 214/1 BS [451 Jan. 1, 1974 FOREIGN PATENTS OR APPLICATIONS923,724 4/1963 Great Britain 294/65 Primary Examiner-Gerald M. ForlenzaAssistant Examiner-George F. Abraham Att0rney--W. T. French et al.

[57] ABSTRACT A high speed labelling machine which picks up and laysdown labels by means of an apertured pressureand-vacuum head includes amonitoring system for assuring against faulty labelling The monitoringsystem employs a pressure switch rather than a vacuum switch to checkfor vacuum during the monitoring operation. Use of a pressure switch asa vacuum detector is made possible by means of a chamber connected tothe head, and to which an auxiliary internal pressure is applied thepressure switch being also connected to the chamber.

4 Claims, 2 Drawing Figures 29 kw? PRESSURE ral SOURCE VAC HEAD AC TUATOR I VACUUM L sou/r05 30 40 Alf? PRESSURE j SUPPLY (LOW) PMENTEU H974EQWDM rullll |||L GHASSAN N. KAHWAT/ ALLEN C. MERCER INVENTORS A rTOR/VEY LABElLlLllNG MAJCHINE Wi'll-l PNEUMATIC MONlTOR BACKGROUND OFTHE INVENTION Machines which are used to apply labels or the like topackages or cartons are often used in high speed operations having ahigh volume of production. These machines often have a movableapplicator head which picks up, prepares, then applies a label to acarton or package. One way to pick up a label and hold it is by means ofa hollow apertured applicator head to which a vacuum is applied. As alabel is moved beneath the head, suction from the vacuum causes thelabel to be drawn up against the head, covering the apertures. Thisblocking of incoming air allows a partial vacuum to be achieved in theapplicator head. The label may then be moistened or heated while thehead is moved into a position for application of the captive label to apackage. When the head and label are in contact with the package, thevacuum is turned off and, simultaneously, a high pressure is introducedinto the head, and the label is blown firmly against the package.

in order to maintain realistic quality control levels and to prevent alarge number of rejects, the performance of the aforesaid machine mustbe continuously monitored. Because machines of this type operate at highspeeds and have a large volume of production, monitoring of the labelapplication operation must occur almost at the instant a label isapplied to a package. if the monitoring apparatus were employed later,by the time a malfunction was detected and an alarm activated, too greata number of defectively labelled packages would have been produced.

A method of detecting the presence of a label in position on theapplicator head is by sensing whether a vacuum has been achieved insidethe head. This is most easily done by connecting a vacuum sensing switchto either the head or to the conduit connecting the head and thepressure sources.

Vacuum sensing switches are theoretically ideal for this application,but in practice their use has often presented problems. One such problemis the high degree of sensitivity that is necessary to detect a slightdrop in pressure. A label in the correct position on the head will causeonly a slight drop from the low pressure created by the suction when nolabel is on the head. Such sensitivity problems are further compoundedwhen a label being held by a head is slightly askew, so that not all thesuction holes are covered, thus causing an even smaller decrease inpressure to be detected. Vacuum sensors which can detect small changesin pressure are notoriously difficult to calibrate and adjust, and tendto be rather costly.

The type of machine on which such vacuum sensors are desired to be usedalso presents a problem: in the normal course of production, thesemachines may be required to use labels having different sizes and shapeswithout changing the applicator head; such different labels will presentnot only different, but also smaller, pressure increments that must bedetected. Detection of such small and varied increments requires eithersubstitution of a different vacuum sensor or the recalibration of theexisting one. Both of the above solutions require the machine to be shutdown for a period, causing a loss of production which is highlyundesirable.

Another problem stemming from the use of vacuum sensing switches istheir relatively slow response time;

that is, the total time it takes to sense a variation in pressure plusthe time it takes for the switch to change states.

As already mentioned, machinery of this type operates at high speeds andcan be made to operate so fast that the slow response time of the vacuumswitch is the limiting factor which prevents further increases inoperating speed. I

These problems associated with vacuum switches have been tolerated inthe past as inherent system limi tations. However, the search for a morereliable, faster operating vacuum switch has been an ongoing project.

SUMMARY OF THE INVENTlON To eliminate the aforesaid problems that havebe come associated with vacuum sensing switches, the invention proposesthe use of a common pressure-sensing switch in combination with anexternal air pressure supply and a specially designed pressure chamber,thereby to remove the troublesome vacuum switch from the system.

Were a pressure-sensing switch to be used as a direct substitution for avacuum switch, it would serve only to indicate an increase in airpressure. However, in a labelling machine of the indicated type, theabsence of high pressure does not indicate the presence of a vacuum (Le,a label in position) hence, such direct substitution will not supply allthe desired information in regard to system performance.

The use of pressure sensing switches immediately overcomes one of thedrawbacks associated with vacuum switches: i.e., response time. Pressureswitches normally have a much faster response time than vacuum switches.One reason for this is that a measureable change in a relatively highpressure represents, for example, at least one pound per square inch,while a measureable change in a relatively low pressure (vacuum)represents a change of less than one-half pound per square inch. Moreforce on the diaphragm of a pressure sensing device will allow thediaphragm to have greater travel and will permit faster switchactuation.

Use of the invention also eliminates difficulties caused by differentsize labels. The external air supply to the pressure chamber isadjustable, and since such air supply controls the level at which thepressure switch changes state, i.e., goes from on to off, the sys tem ofthe invention can easily be made to recognize pressure changes caused byany size label. Such adjustments may be made almost instantly by settingthe external pressure to a predetermined level, thereby obviating thenecessity for any machine shutdown.

The specially shaped chamber is provided with a small orifice at theconnection with the conduit leading to the applicator head, thuseffectively isolating the sensing apparatus from the main system andpreventing such apparatus from loading the system.

By allowing the external air pressure to remain on always to pressurethe chamber, the pressure switch tends to be actuated at all times, airpassing out of the chamber being expelled from the applicator headapertures. Because of the small orifice at the point where the chamberjoins the indicated conduit, when the high pressure air is applied tothe head, most of it will not enter the chamber but will be expelledfrom the applicator head. When the vacuum :is applied, air is both drawnin through the holes in the applicator head and removed from the chamberthrough the small-sized orifice. By providing the correct size for suchorifice, and by adjusting the external air pressure being fed into thechamber, the pressure switch can be made to change states only when thevacuum is on and a label is affixed over the apertures in the applicatorhead. Another orifice is also provided in the chamber to act as apressure relief, since the chamber is alternately pressurized andevacuated. Means are also providing for producing an alarm signal and/orstopping the machine when a nonconformance condition is detected, e.g.,when a label is stuck to the head when it should have been applied to apackage.

To illustrate the advantages of the invention, it is shown and discussedas means for improving an existing machine, but it should be understoodthat the invention is not limited to this type of application. Theinvention provides apparatus whereby a sensitive pressure switch isadapted to perform, with greater sensitivity than the function of avacuum switch.

The invention will be described with reference to the figures, wherein:

FIG. 1 is a schematic block diagram illustrating apparatus embodying theinvention, and

FIG. 2 illustrates waveforms useful in describing the invention.

DESCRlPTlON OF THE PREFERRED EMBODlMENT Referring to FIG. 1, a web ofmaterial 21 having labels printed thereon is caused to move by means ofa drive roller 22', as the web moves, a photoelectric cell 23 senses thediscrete labels of the web. The output signal from the photoelectriccell is used to synchronize the cutting of the web 21 into'detachedlabels, such cutting being accomplished by a chopper 25. After beingseparated from the web 21, an individual label 24 may be moved to theposition of an applicator head 26 by any suitable means such as rollersor the like.

It should be noted that means for providing the correct sequence ofmachine operations is shown as a controller 27; and such controller maybe in the form of a common timing sequencer consisting of rotating camsand switches, or it might be an electronic timer with no moving parts.

Since an objective of the invention is to detect the presence of a labelon the applicator head 26 at the earliest possible time, when themachine is first started, an adjustable air pressure supply 30 connectedto a chamber 31 is turned ON. The chamber 31 is connected to a standardpressure sensitive switch assembly 32 having a displaceable diaphragm 33which operates a switch 34. Such switch 34 is electrically connected tologic 35 for indicating the state of the switch assembly 32 The logic35, depending on the operation of the switch 34, operates an alarm 36and a machine stop command signal line 37. The chamber 31 is connectedvia a suitably small orifice 42 to a main conduit 38 which runs to theapplicator head 26. The adjustable air pressure 30, when ON, causes thepressure inside the chamber 31 to be sufficiently high to cause thediaphragm 33 to displace and place the arm of the switch 34 in contactwith a contact 1. This may or may not indicate a malfunction, dependingon the state of the alarm logic 35 and the controller 27.

As the cut label 24 moves into position with respect to the applicatorhead 26, a suction is applied to the head through the main conduit 38 byactuation of a solenoid valve 28 which is connected between the mainconduit 38 and a vacuum source 40. Upon applying the vacuum, air issucked in through holes 41 in the applicator head 26; and the pressureinside the main conduit 38 is lowered. The chamber 31 also tends to beevacuated, causing its pressure to be lowered accordingly. Because ofthe size of the orifice 42 and the amount of air being supplied by theadjustable pressure supply 30, the low pressure caused by the vacuumsource 40 is not sufficient to overcome the higher pressure beingsupplied to the chamber. This is a key feature of the invention. Afterthe label 24 has moved into position, the holes 41 in the applicatorhead will be covered and the pressure inside the head 26 and the mainconduit 38 will drop even lower; and as this pressure drops, it tends toovercome the high pressure in the chamber 31, creating a partial vacuumand causing the diaphragm 33 to relax, thereby placing the arm of theswitch. 34 in contact with a contact 2. This indicates the presence of arelative vacuum at the head 26 and hence the presence of a label. If asequencing controller 27 has signalled the alarm logic 35 that a labelis required to be on the head at this time (Test 1), then the switch 34is in its correct state and no malfunction condition will be indicated.If a label is not in the required position, the suction created byvacuum source 40 will not be sufficient to overcome the pressure in thechamber 31; the diaphragm 33 will not relax; and the switch 34 will notbe in the correct state, when compared with the signalv from the alarmlogic 35. This will indicate a malfunction and the machine will becommanded to stop.

The operation thus having passed its first test successfully, i.e., alabel 24 is present at the correct point in the cycle, the label 24 isheated to allow it to adhere to a carton or package 45 which is beingpositioned for labelling by a conveyor belt 50. Label heating isaccomplished by heater wires 44 located inside the applicator head 26,the temperature being controlled by a suitable heater control 43. As thelabel is being heated, the applicator head 26 is lowered towards thepackage 45 by suitable means 52. At the instant that the applicator head26 contacts the package, the vacuum holding the label to the head isremoved by closing the solenoid valve 28 and, at substantially the sametime, applying a high pressure to the applicator head by turning(opening) a solenoid valve 29. The solenoid valve 29 is connected by asuitable conduit between a high pressure air supply 6411 and the mainconduit 38.

When high pressure air is applied to the head 26, the label 24 is forcedaway from the head and into contact with the package 45, to which itbecomes firmly affixed, by the high pressure air being expelled from theholes 41 in the applicator head. The high pressure is then removed fromthe head 26 by closing the solenoid valve 29, and suction is thenapplied again to the applicator head by opening the solenoid valve 28. Asignal from the sequence controller 27 to the applicator head actuator52 causes it to begin to reposition the head 26 to receive the nextlabel from the chopper 25.

Since an objective of the invention is to prevent the production ofpackages without labels, the applicator is checked (Test 2) to determinethat the label 24 is, in fact, gone, i.e., applied to a package 45:Suction having been applied to the head 26, air enters the holes 41 andcauses the pressure in the main conduit 38 to drop, but not sufficientlyto overcome the relatively high pressure in the chamber 31 caused by thepressure supply 30. The pressure in the chamber 31 causes the diaphragm33 to be displaced, and causes the arm of the switch 34 to come intocontact with the contact l, thereby indicating at this time, per thealarm logic 35, the correct state for the head 26, i.e., no labelpresent. Were a label to be stuck on the applicator head 26, however, avacuum would exist sufficient to cause the pressure in the chamber 31 tobe overcome and to cause the arm of the switch 3d to be in contact withcontact 2, whereby the alarm logic 35 would cause a malfunction to beindicated and the machine stopped.

in regard to Fit]. 2, the relative states of the two solenoids 2% and 29are shown in chart A as they are energized and de-energized through onecycle of the labelling machine. At the point indicated where neithersolenoid is energized, a label is being positioned beneath the holes inthe applicator head 26. The vacuum is then turned ON and the label iscaptured by the head. When the label is seized by the applicator head,the head is caused to move downward toward the package to be labelled,as indicated by waveform B, FIG. 2. At this time it is desired to testfor the presence of a label (Test 1).

Test ll having been successfully passed, the label is applied to thepackage by turning OFF the vacuum and turning ON the pressure as shownby waveform A of FIG. 2. After the label is applied to the package, thehead is returned upward to its up position. At this time, the head ischecked (Test 2) to determine if the label has indeed been applied.

if the label has been applied, the vacuum (applied during Test 2) in theline 38 is insufficient to overcome the pressure of the supply 30,causing operation of the alarm 36 as described above. But assuming thatTest 2 is completed without alarm, the vacuum is turned OFF, and thenext label moved into position beneath the applicator head; the vacuumbeing thereafter again applied, causing the pressurevacuum cycle tobegin anew.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:

ll. An apparatus for handling label-like elements, comprising:

a hollow applicator head having at least one external aperture into thehollow thereof,

means for selectively applying vacuum and pressure to said head,

means for positioning an element to be handled so that it covers saidaperture, whereby the element may be picked up and laid down by saidhead,

a pressurized chamber pneumatically connected continuously to said headthrough an orifice of selected size, and

a pressure switch pneumatically connected to said chamber for indicatingpressure changes in said chamber resulting from applying said vacuum tosaid head.

2. The apparatus of claim 1 further comprising means responsive to aposition of said pressure switch for generating a signal indicating amalfunction of said apparatus.

3. The apparatus of claim 2 further comprising means responsive to saidsignal for interrupting the operation of said apparatus.

4. The apparatus of claim 1 further comprising means for maintaining thepressure of said chamber within selected limits,

wherein the size of said orifice is such that said pressure in saidchamber decreases to a level sufficient to operate said pressure switchonly when the said element completely covers said aperture or aperturesin said applicator head.

* =l 1F =l

1. An apparatus for handling label-like elements, comprising: a hollowapplicator head having at least one external aperture into the hollowthereof, means for selectively applying vacuum and pressure to saidhead, means for positioning an element to be handled so that it coverssaid aperture, whereby the element may be picked up and laid down bysaid head, a pressurized chamber pneumatically connected continuously tosaid head through an orifice of selected size, and a pressure switchpneumatically connected to said chamber for indicating pressure changesin said chamber resulting from applying said vacuum to said head.
 2. Theapparatus of claim 1 further comprising means responsive to a positionof said pressure switch for generating a signal indicating a malfunctionof said apparatus.
 3. The apparatus of claim 2 further comprising meansresponsive to said signal for interrupting the operation of saidapparatus.
 4. The apparatus of claim 1 further comprising means formaintaining the pressure of said chamber within selected limits, whereinthe size of said orifice is such that said pressure in said chamberdecreases to a level sufficient to operate said pressure switch onlywhen the said element completely covers said aperture or apertures insaid applicator head.